Method of making an abrasive wheel

ABSTRACT

An abrasive wheel in which abrasive surfaced flexible leaves extend radially from a stud or mandrel, the base edges of the leaves being bonded directly to the surface of the stud. The method of making such a wheel includes the steps of forming a straight stack of abrasive leaves, cutting at least one groove down the edge of the stack which is to be the base of the leaves in the completed wheel, adhesively disposing a string in the groove to hold the leaves in assembly for further handling, the string and adhesive when cured being flexible and reposing within the groove, applying to said edge of the stack, and preferably also to the stud, a tenacious bonding agent lacking flexibility when cured, wrapping the stack around a stud with the edge which is coated with the bonding agent in direct contact with the stud, and providing for the bonding agent to harden and permanently adhere the edge made up of the base ends of the abrasive leaves to the stud.

Hasegawa [4 1 Mar. 5, 1974 METHOD OF MAKING AN ABRASIVE WHEEL [75] Inventor:

[73] Assignee: Merit Abrasive Products, Inc.,

Compton, Calif.

Hiroshi Hasegawa, Whittier, Calif.

22 Filed: May 3,1972

21 Appl. No.: 250,049

[52] US. Cl. 51/297, 51/334 [51] Int. Cl B24d 11/00 [58] Field of Search 51/334-337, 293,

[56] References Cited 7 Burns 51/337 X Primary Examiner-Othell M. Simpson Assistant Examiner-Nicholas P. Godici Attorney, Agent, or Firm-Smyth, Roston & Pavitt [57] ABSTRACT An abrasive wheel in which abrasive surfaced flexible leaves extend radially from a stud or mandrel, the base edges of the leaves being bonded directly to the surface of the stud.

The method of making such a wheel includes the steps of forming a straight stack of abrasive leaves, cutting at least one groove down the edge of the stack which is to be the base of the leaves in the completed wheel, adhesively disposing a string in the groove to hold the leaves in assembly for 'further handling, the string and adhesive when cured being flexible and reposing within the groove, applying to said edge of the stack, and preferably also to the stud, a tenacious bonding agent lacking flexibility when cured, wrapping the stack around a stud with the edge which is coated with the bonding agent in direct contact with the stud, and providing for the bonding agent to harden and permanently adhere the edge made up of the base ends of the abrasive leaves to the stud.

7 Claims, 7 Drawing Figures 1 METHOD OF MAKING AN ABRASIVE WHEEL BACKGROUND OF THE INVENTION Abrasive wheels formed of a multiplicity of abrasive coated flaps arranged in annular pattern around a hub or mandrel are well known-They are used for surface finishing of metal, plastic, rubber and wood, such as grind-blending, satin finishing, cleaning, polishing, de-

. burring and surface smoothing.

- of 1 inch or 1 /2 inch, and an axial length of 1 inch more or less.

One method which has been practiced for making small wheels was to take'a stack of leaves and glue a piece of cotton tape to one edge which was to become the wall of the central annulus.

A groove was then cut in one side of the stack (an end ofthe completed wheel) near the taped edge. Adhesive was applied either to the knurled surface of the stud or to the cotton tape, or both, and then the stack was wrapped around the stud and a ring inserted in the groove to hold the leaves in circular array on the stud while the adhesive cured.

For reinforcement it was known to pour epoxy into the end of the wheel at the base area of the leaves.

A weakness of this type of wheel construction was that the leaves were adhered to the tape with white vinyl glue to afford necessary flexibility) and the integrity of the wheel depended upon the insertion of epoxy at the end making a leaf to leaf bridge all the way around the wheel; Intervention of the cotton tape pre-' vented a direct bond between the inner edge of the leaves and the stud itself. The ring served no functional purpose in the wheel and operation because it was simply a fixture (being a spring type ring) to hold the leaves in a circle until the epoxy could be inserted and cured.

Another prior practice was to assemble the leaves in a straight form, apply adhesive to one edge of the assembly, allowing it to dry sufficiently to hold the leaves together and then forming an annulus around a circular cardboard core. This was attended by deficiencies generally similar to that described above.

It has been known also to fill an area between the inner ends of the leaves and the outer surface of the stud or mandrel with thick packing of phenolic or other resin, and provide flanges of such material at the ends, thus forming a sort of spool to which the inner ends of the leaves were bonded and the bore of the spool being bonded to the stud. Such practice reduced the proportionate length of the abrasive leaves available for work and also presented a problem of arranging a truly circular pattern.

SUMMARY OF THE INVENTION The present invention involves cutting one or more grooves down the edge of the stack which is to be the center section of the wheel. A string is glued in each groove, using an adhesive which when cured possesses sufficient flexibility or resiliency to permit wrapping the stack around a stud or mandrel of small diameter. The string is to retain the stack intact for handling and assembly on the stud.

After the adhesive on the string has cured sufficiently for the purpose, a permanent strong bonding agent such as an epoxy is applied to the edge of the stack so that the entire surface of the-edge is coated with a film and some of the epoxy has penetrated slightly between the leaves. Preferably, epoxy is also applied to the stud.

The stack is then wrapped around the stud, and the formed assembly is held tightly in position on the stud by any suitable means, for example a cord or a rubber band, while the epoxy hardensl The wheel thus formed embodies a truly circular arrangement of leaves with their inner ends bonded not only together but directly to the stud through the film of epoxy with no intervening tape or cardboard or plastic filler in the form of a spool or hub.

BRIEF DESCRIPTION OF THE DRAWING -manent bonding agent has been applied.

FIG. 6 is a perspective view of the stack of FIG. 5 wrapped around a stud and constrained in position for curing of the bonding agent.

FIG. 7 is a fragmentary section taken on line 7-7 of FIG. 2. Y

DESCRIPTION OF THE PREFERRED EMBODIMENT Sheets of flexible material carrying suitable abrasive on one surface are cut to provide leaves 15 of uniform shape and size.

and arranged in a flat plane. Optionally the stack may be composed of sufficient leaves for a plurality of wheels and subsequently be separated into the requisite units.

One or more grooves 18 are cut by a saw or routing tool or burned in the edges 17 generally parallel to the ends 19 and 20.

An adhesive 22 of a type which can be flexed when cured is spread in each groove, and a flexible string or cord 23 is seated in the groove for attachment by aid of the adhesive to the groove edges of the leaves. A white vinyl glue is an example of a suitable adhesive.

The relative depth of the grooves and the diameter of the string should be such that the string does not extend beyondthe plane presented by the edges 17. This is desired so that the edges of the leaves forming the stack may be in direct contact through a film of epoxy with a stud or mandrel 25 of the wheel 26 when completed. The stud should have a knurled surface 27 for better retention of a bonding agent to be used.

After the adhesive attaching the string to the leaves has cured, a stack (shown in FIG. 4) having the requisite linear measurement for a wheel is taken, and a permanent strong and hardening bonding agent such an epoxy is applied as a film 30 to the entire exposed surface of the edges 17. This can be done by brushing, spraying, or dipping. It should be applied in sufficicnt quantity for the epoxy to penetrate slightly between the leaves adjacent the edges 17 as indicated at 31. It is desirable also to dip the knurled section of the stud in epoxy.

Theassembly is then wrapped around the stud 25 with the edges 17 in direct contact through the epoxy film with the knurled surface of the stud. The wrapped around assembly is circumferen-tially constrained to press the epoxy coated edges 17 against the stud while the epoxy sets/This may be done by encircling the leaves with a rubber band 33, or a cord or circular clamp.

When the epoxy hardens, the edges 17 of the leaves are bound into a nonflexible annulus 32 by the epoxy film and epoxy between the leaves, and in intimate and permanent contact with the stud. The string or strings 23 present so slight a surface that any interference with the direct bonding of the leaves to the stud is insignificant. i

' The stud includes a projecting end 34 of any suitable thread or configuration to function as a shank for chucking in a power tool, and a flange 35 divides the end from the knurled section.

A wheel thus constructed provides maximum durability, and by requiring a minimal proportion of each leaf for attachment to the stud, a very large proportion of each leaf is available for service. The epoxy possesses greater tensile strength than the abrasive surfaced leaves, its adhering properties are tenacious, and a thin film will secure the leaves to the stud with a permanency which insures that theleaves wear out in service rather than become detached under the stress of rotational contact with the work pieces.

Although I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention.

I claim 1. A method of making an abrasive wheel comprising the steps of: assembling a plurality of abrasive surfaced flexible leaves in a stack of generally rectangular block form with the edges which are to be in the center section of the wheel exposed in a generally flat plane, cutting a groove in said edges, adhesively securing a flexible string-like member in the groove with an adhesive which can be flexed when cured whereby the stack is united and can be handled intact, after such curing applying to the entire area of said exposed edges a film of bonding agent which is hard and nonflexible when cured, wrapping the stack around a stud with said edges contiguous to the surface of the stud and absent intervening elements, and constraining the wrapped around stack against the stud to hold said edges against the stud while the bonding agent hardens.

2. A method as defined in claim 1 which includes applying a thin film of the last named bonding agent to the surface of the stud before wrapping the stack around the stud.

3. A method as defined in claim 1 wherein the bonding agent is applied in sufficient quantity to penetrate slightly between adjacent leaves in the region of the edges.

4. A method as defined in claim 1 wherein an epoxy is used as the bonding agent. 7

5. A method as defined in claim 3 wherein an epoxy is used as the bonding agent, and in curing forms a thin annulus with minute integral extensions between adjacent inner edge areas of the leaves.

6. A method as defined in claim 1 wherein the annulus defined by the outer edges of the adjacent leaves is constrained to press against the stud the edges of the leaves to which the bonding agent has been applied.

7. A method as defined in claim 5 wherein the annulus defined by the outer edges of the adjacent leaves is constrained to press against the stud the edges of the leaves to which the epoxy has been applied. 

2. A method as defined in claim 1 which includes applying a thin film of the last named bonding agent to the surface of the stud before wrapping the stack around the stud.
 3. A method as defined in claim 1 wherein the bonding agent is applied in sufficient quantity to penetrate slightly between adjacent leaves in the region of the edges.
 4. A method as defined in claim 1 wherein an epoxy is used as the bonding agent.
 5. A method as defined in claim 3 wherein an epoxy is used as the bonding agent, and in curing forms a thin annulus with minute integral extensions between adjacent inner edge areas of the leaves.
 6. A method as defined in claim 1 wherein the annulus defined by the outer edges of the adjacent leaves is constrained to press against the stud the edges of the leaves to which the bonding agent has been applied.
 7. A method as defined in claim 5 wherein the annulus defined by the outer edges of the adjacent leaves is constrained to press against the stud the edges of the leaves to which the epoxy has been applied. 